EP0278777B1 - Infrarotteleskop mit zweifacher Vergrösserung - Google Patents
Infrarotteleskop mit zweifacher Vergrösserung Download PDFInfo
- Publication number
- EP0278777B1 EP0278777B1 EP19880301191 EP88301191A EP0278777B1 EP 0278777 B1 EP0278777 B1 EP 0278777B1 EP 19880301191 EP19880301191 EP 19880301191 EP 88301191 A EP88301191 A EP 88301191A EP 0278777 B1 EP0278777 B1 EP 0278777B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- telescope
- lens
- lens group
- magnification
- movable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000009977 dual effect Effects 0.000 title claims description 10
- 239000000463 material Substances 0.000 claims description 7
- 230000004075 alteration Effects 0.000 claims description 5
- 230000003287 optical effect Effects 0.000 claims description 4
- 229910052732 germanium Inorganic materials 0.000 claims description 3
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 3
- 230000005499 meniscus Effects 0.000 description 9
- PFNQVRZLDWYSCW-UHFFFAOYSA-N (fluoren-9-ylideneamino) n-naphthalen-1-ylcarbamate Chemical compound C12=CC=CC=C2C2=CC=CC=C2C1=NOC(=O)NC1=CC=CC2=CC=CC=C12 PFNQVRZLDWYSCW-UHFFFAOYSA-N 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 210000001747 pupil Anatomy 0.000 description 5
- 230000005855 radiation Effects 0.000 description 3
- 230000004323 axial length Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 239000005387 chalcogenide glass Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/14—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation
- G02B13/146—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation with corrections for use in multiple wavelength bands, such as infrared and visible light, e.g. FLIR systems
Definitions
- This invention concerns improvements in or relating to infra-red telescopes and more particularly to dual magnification infra-red telescopes.
- Normally infra-red telescopes have a zoom facility providing for variation in the magnification from, for example, x 5 to x 20 or more.
- the development history of such telescopes has been characterised by the goal of increasing compactness such that progressive designs have generally tended to decrease the axial length of the telescope whilst maintaining or even improving upon the optical performance characteristics.
- UK patent 2126370B shows a mechanically compensated zoom lens having a magnification adjustable between a first low value and a second higher value, the lens comprising a fixed front lens component which at the higher magnification gives under-correct third and fifth order spherical aberration, a negative lens component which is movable relative to the front lens component and which at the higher magnification gives compensating over-correct third and fifth order spherical aberration, a positive lens component movable relative to the front lens component and the negative lens component, and a rear lens component fixed relative to the front lens component.
- the afocal telescope lens described in UK patent 2126370B has typically an axial length of some 380 mm, thus representing for such a zoom telescope a particularly compact configuration.
- the present invention has as its object the provision of a dual magnification telescope rather than a zoom telescope, which is also particularly compact, even when compared to the zoom telescope of UK patent 2126370B.
- the present invention resides in part in the appreciation that for some applications where a zoom requirement is not necessary but a dual magnification is, considerable compactness and simplification of the design can be achieved with the use of only a single lens element to provide focusing of the telescope at the two required magnifications but not specifically in between the two magnifications.
- a compact dual magnification infra-red transmitting telescope which is settable either to a fixed first magnification value or to a fixed second magnification value
- the telescope comprises a front lens group of positive power, a rear lens group of positive power, an eyepiece lens group, and a single movable lens element located between the front lens group and the rear lens group, the movable lens element being of negative power and movable axially along the principal optical axis of the telescope from a first position at which the telescope has the first value of magnification to a second position at which the telescope has the second value of magnification, the telescope being substantially out of focus at intermediate positions of the movable lens element between the said first and second positions.
- the front lens group may comprise a first positively powered lens element and a second negatively powered lens element.
- the movable lens element component may conveniently be shaped to correct aberration contributions resulting from the front lens group at each value of magnification, such as by being of bi-concave form.
- the rear lens group may conveniently include an achromatising lens element, such as a negative lens element, which may be of zinc selenide material.
- the rear lens group may further comprise a total of four lens elements, the first two of which are of positive power followed by an achromatising negative lens element, and then a fourth negative lens element, which fourth negative lens element may provide control over entrance pupil position to thereby minimise the entrance lens diameter requirement.
- the achromatising lens element of zinc selenide may constitute the second lens element of the rear lens group or even the first lens element of the lens group.
- the eyepiece group may be of overall positive power and comprise three lens elements.
- the overall telescope design may be substantially of germanium material, apart from the achromatising lens element in the rear lens group which, as stated, may conveniently be of zinc selenide material.
- the telescope may be athermalised for focus by modification of the extremes of axial position of the single lens element.
- the front lens group or the rear lens group, or possibly both, may be movable for athermalisation purposes.
- front and rear are used in the sense that the front of the lens faces towards the object and the rear of the lens faces towards the exit pupil.
- eyepiece the ultimate image is in fact not viewed by the human eye, since it is in the infra-red region of the spectrum but is, for example, scanned across an infra-red detector array.
- the lens may be particularly designed so that it operates within the 8-12 micron waveband and the materials of the lens elements are selected accordingly to have a useful transmission of radiation at the required relevant wavelengths.
- the spaces between the solid elements are preferably occupied by gas, conveniently air, and the refracting surfaces of the lens components are preferably all of spherical curvature.
- the total length of the assembly of the lens groups can be as little as 220 mm or less.
- the infra-red dual magnification telescope shown in Figures 1 and 2 comprises an "eyepiece” lens combination generally indicated “E” and an objective lens combination generally indicated "0".
- the objective lens combination produces an intermediate real image indicated “I”, which is "viewed” through the "eyepiece” lens combination.
- the objective lens combination comprises a two-element doublet lens, the first element 1 of which is a meniscus element of positive power with its convex surface facing forwardly. Behind the element 1, the element 2 is of negative power and of meniscus shape convex towards the front.
- the group 1,2 is of overall positive power.
- a negatively powered single lens element 3 of bi-concave form is provided for dual-magnification and is movable from the position shown in Figure 1, representing a x 10 magnification, to the position shown in Figure 2, representing a x 5 magnification.
- the rear lens group of this embodiment of the invention comprises four lens elements, 4, 5, 6 and 7 respectively.
- Element 4 is of meniscus form with its concave surface facing forwardly.
- the element 5 is of meniscus form with its convex surface facing forwardly.
- Elements 4 and 5 are each of positive power.
- Element 6 is negatively powered and of meniscus form with its convex surface facing forwardly and, unlike the other lenses in the telescope, is of zinc selenide material in order to achromatise the telescope.
- Lens element 7 is a negatively powered lens of meniscus form.
- the eyepiece lens system comprises a positively powered meniscus lens element 8 with its concave surface facing forwardly, a positively powered meniscus lens element 9 with its convex surface facing forwardly and a positively powered meniscus lens element 10, also with its convex surface facing forwardly.
- the exit pupil of the eyepiece lens group is shown at 11.
- the radiation passing through the exit pupil would be incident on a detector for detecting incoming infra-red radiation.
- a particular example of lens in accordance with the embodiment shown with reference to Figure 1 has numerical data as follows, the refractive surfaces being indicated successively as R1 to R20 from the back of the telescope to the front of the telescope, the axial thickness/separation in the actual distance to the next succeeding surface and the dimensional units are in millimetres.
- the axial separations between the surfaces R14/R15 and R16/R17 are dependent upon the magnification setting i.e. x 10 in the table.
- the corresponding axial separation for the x 5 magnification are, as between surfaces R14/R15 some 40.99 mm and as between surfaces R16/R17 some 16.48 mm.
- the single element lens component 3 has a range of axial movement between the x 10 setting and the x 5 setting of some 32.48 mm.
- the above example has lens elements which are all made up of germanium with the exception of the achromatising element 6 which is of zinc selenide, although another suitable dispersive material, such as Chalcogenide glass designated BS1 (manufactured by Barr & Stroud Limited) could be used if desired.
- BS1 Chalcogenide glass
- the spaces between the solid lens elements are air and the focal lengths of the lens elements are as follows:-
- the "eyepiece" lens E consisting of elements 8, 9 and 10, has a focal length of 15.69.
- the fixed rear positive group consisting of elements 4, 5, 6 and 7 has a focal length of 24.81.
- the front positive group consists of elements 1 and 2 and has a focal length of 145.15.
- the refractive surfaces R1 to R20 in the above example are all of spherical curvature and the lens is designed to operate over an 8 to 12 micron waveband.
- the telescope according to the above example has an overall length from front to back, including the distance to exit pupil 11, of only about 192 mm. It will be appreciated by those skilled in the art that this represents considerable compactness in design, even when compared with conventional dual-magnification telescopes which operate in the visible portion of the spectrum.
- a further example in accordance with the embodiment shown in Figures 3 and 4 is of essentially similar design to that shown in Figures 1 and 2 with the exception that this second embodiment is designed to provide a dual magnification between x 10 and 3.5 and also that the achromatising lens element of zinc selenide is in this particular example lens element numbered 4, rather than 6 in the first embodiment.
- Corresponding numerals are used in the second embodiment of the example, to those used in the first embodiment.
- the second embodiment of the invention has the following numerical data: Example 2 Surface Radius of Curvature Axial thickness/Separation R1 -57.15 4.57 R2 -43.85 1.00 R3 -195.17 4.57 R4 -136.17 0.50 R5 31.22 7.27 R6 31.22 50.56 R7 -42.29 3.05 R8 -70.20 25.16 R9 -70.20 5.84 R10 -53.99 2.00 R11 -51.17 3.81 R12 -60.23 0.50 R13 250.31 5.84 R14 -842.76 7.60 R15 -202.42 2.17 R16 251.61 54.52 R17 -108.25 3.81 R18 -183.92 2.00 R19 -197.84 13.60 R20 -100.00 0.00 Total: 196.27 mm
- the axial separations between the surfaces R14/R15 and R16/R17 are given for the x 10 magnification setting.
- the corresponding axial separations for the x 3.5 magnification setting is, as between surfaces R14/R15 some 48.49 mm and as between surfaces R16/R17 some 13.63 mm.
- the single element lens component 3 has a range of axial movement between the two magnification settings of some 40.89 mm.
- the focal lengths of the respective individual lens elements in the second example are as follows:-
- the focal length of the "eyepiece" lens E consisting of elements 8,9 and 10 is 20.56.
- the focal length of the rear group consisting of elements 4,5,6 and 7 is 35.90.
- the focal length of the front group consisting of elements 1 and 2 is 136.41.
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
- Telescopes (AREA)
Claims (9)
- Ein Infrarot-Transmissionsteleskop weist eine vordere Linsengruppe (1, 2) mit positiver Brechkraft, eine hintere Linsengruppe (4, 5, 6, 7) mit positiver Brechkraft, eine Augenlinsengruppe (8, 9, 10) und eine bewegbare Linseneinrichtung zwischen der vorderen Linsengruppe und der hinteren Linsengruppe zum Verändern der Vergrößerung des Teleskops auf,
dadurch gekennzeichnet, daß das Teleskop ein Teleskop mit zweifacher Vergrößerung ist, daß die bewegbare Linseneinrichtung ein einzelnes bewegbares Linsenelement (3) umfaßt, das negative Brechkraft aufweist und entlang der optischen Achse des Teleskops von einer ersten Position, an der das Teleskop einen ersten festen Vergrößerungswert aufweist, zu einer zweiten Position, an der das Teleskop einen zweiten festen Vergrößerungswert aufweist, axial bewegbar ist, und daß das Teleskop an Zwischenpositionen zwischen den ersten und zweiten Positionen des bewegbaren Linsenelements (3) weitgehend defokussiert ist. - Teleskop nach Anspruch 1, dadurch gekennzeichnet, daß die vordere Linsengruppe ein erstes Linsenelement (1) mit positiver Brechkraft und ein zweites Linsenelement (2) mit negativer Brechkraft umfaßt.
- Teleskop nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die hintere Linsengruppe (4, 5, 6, 7) ein achromatisierendes Linsenelement umfaßt.
- Teleskop nach Anspruch 3, dadurch gekennzeichnet, daß die hintere Linsengruppe vier Linsenelemente (4, 5, 6, 7) umfaßt.
- Teleskop nach einem vorhergehenden Anspruch, dadurch gekennzeichnet, daß die Augenlinsengruppe positive Brechkraft aufweist und drei Linsenelemente (8, 9, 10) umfaßt.
- Teleskop nach Anspruch 1, dadurch gekennzeichnet, daß das bewegbare Linsenelement (3) zum Korrigieren von durch die vordere Linsengruppe (1, 2) verursachter Aberration ausgebildet ist.
- Teleskop nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß es in dem 8 bis 12 µm-Wellenband betreibbar ist und daß zumindest die Mehrheit seiner Linsenelemente aus Germanium-Material besteht.
- Teleskop nach einem vorhergehenden Anspruch, dadurch gekennzeichnet, daß der Aufbau der Linsen des Teleskops eine gesamte Länge von weniger als 220 mm aufweist.
- Teleskop nach einem vorhergehenden Anspruch, dadurch gekennzeichnet, daß die relative Position des bewegbaren Linsenelements (3) bzgl. eines Elements oder Elementen einer oder sowohl der vorderen Linsengruppe (1, 2) als auch der hinteren Linsengruppe (4, 5, 6, 7) zu Athermalisierungszwecken um einen im Vergleich zu der Bewegung der Vergrößerungsveränderung kleinen Wert variierbar ist.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8703402 | 1987-02-13 | ||
GB878703402A GB8703402D0 (en) | 1987-02-13 | 1987-02-13 | Dual magnification infra-red telescope |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0278777A2 EP0278777A2 (de) | 1988-08-17 |
EP0278777A3 EP0278777A3 (en) | 1990-01-24 |
EP0278777B1 true EP0278777B1 (de) | 1993-12-15 |
Family
ID=10612287
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19880301191 Expired - Lifetime EP0278777B1 (de) | 1987-02-13 | 1988-02-12 | Infrarotteleskop mit zweifacher Vergrösserung |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0278777B1 (de) |
DE (1) | DE3886232T2 (de) |
GB (2) | GB8703402D0 (de) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4989962A (en) * | 1988-10-31 | 1991-02-05 | Hughes Aircraft Company | Dual band/dual FOV infrared telescope |
GB2244344B (en) * | 1990-05-18 | 1993-09-29 | Gec Ferranti Defence Syst | Infra-red zoom lens |
US5894371A (en) * | 1997-06-06 | 1999-04-13 | Alliedsignal, Inc. | Focus mechanism for varifocal lens |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4383727A (en) * | 1979-08-08 | 1983-05-17 | Pilkington P.E. Limited | Infra-red optical systems |
GB2102588B (en) * | 1981-07-01 | 1984-12-19 | Barr & Stroud Ltd | Afocal telescope containing three lens eyepiece |
GB2126370B (en) * | 1982-09-04 | 1986-03-05 | Pilkington Perkin Elmer Ltd | Infra-red objective zoom lenses |
FR2586828B1 (fr) * | 1985-08-29 | 1988-08-12 | Angenieux P Ets | Objectif a infra-rouge, a distance focale variable. |
-
1987
- 1987-02-13 GB GB878703402A patent/GB8703402D0/en active Pending
-
1988
- 1988-02-12 GB GB8803264A patent/GB2201011B/en not_active Expired - Lifetime
- 1988-02-12 EP EP19880301191 patent/EP0278777B1/de not_active Expired - Lifetime
- 1988-02-12 DE DE19883886232 patent/DE3886232T2/de not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
GB8703402D0 (en) | 1987-04-08 |
EP0278777A2 (de) | 1988-08-17 |
GB2201011A (en) | 1988-08-17 |
GB2201011B (en) | 1991-01-09 |
DE3886232T2 (de) | 1994-04-28 |
GB8803264D0 (en) | 1988-03-09 |
EP0278777A3 (en) | 1990-01-24 |
DE3886232D1 (de) | 1994-01-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP0171903B1 (de) | Infrarotobjektive | |
US4971428A (en) | Catadioptric zoom lens | |
EP0367197B1 (de) | Zweiband-Infrarotfernrohr | |
US3947084A (en) | Long-wave infrared afocal zoom telescope | |
JP2524612B2 (ja) | 赤外アフォ―カルズ―ム式テレスコ―プ | |
US4443068A (en) | Reflecting telephoto zoom lens system | |
JPH07140386A (ja) | インナーフォーカス方式の望遠ズームレンズ | |
US4235508A (en) | Dual focal length objective | |
US4199217A (en) | Infra-red optical systems | |
US5548439A (en) | Three field of view refractive infrared telescope with fixed medium filed of view | |
US4676581A (en) | Infra-red lenses | |
US5022724A (en) | Zoom system | |
JPH0527172A (ja) | ズームレンズ | |
US5381269A (en) | Zoom lens | |
EP0278777B1 (de) | Infrarotteleskop mit zweifacher Vergrösserung | |
US6057960A (en) | Modular infrared Kepler telescope | |
US4383727A (en) | Infra-red optical systems | |
US6118578A (en) | Simplified dual field of view afocal | |
US4311367A (en) | Wide angle photographic lens | |
US4359272A (en) | Internal focusing telephoto lens | |
US3848967A (en) | Compact seven element zoom lens with optical compensation | |
US4230397A (en) | Large aperture extended range zoom lens | |
JP2503510B2 (ja) | 望遠ズ−ムレンズ | |
US4948239A (en) | Zoom lens | |
US6058269A (en) | Oscillation isolating attachment lens system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): DE FR IT NL SE |
|
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): DE FR IT NL SE |
|
17P | Request for examination filed |
Effective date: 19900718 |
|
17Q | First examination report despatched |
Effective date: 19920515 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): DE FR IT NL SE |
|
ITF | It: translation for a ep patent filed |
Owner name: JACOBACCI CASETTA & PERANI S.P.A. |
|
REF | Corresponds to: |
Ref document number: 3886232 Country of ref document: DE Date of ref document: 19940127 |
|
ET | Fr: translation filed | ||
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
EAL | Se: european patent in force in sweden |
Ref document number: 88301191.8 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: SE Payment date: 19950215 Year of fee payment: 8 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 19950228 Year of fee payment: 8 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Effective date: 19960213 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Effective date: 19960901 |
|
NLV4 | Nl: lapsed or anulled due to non-payment of the annual fee |
Effective date: 19960901 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 19990209 Year of fee payment: 12 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 19990223 Year of fee payment: 12 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20001031 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20001201 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED. Effective date: 20050212 |